Compounds useful as inhibitors of atr kinase

A compound of formula I-A:

• or a pharmaceutically acceptable salt or prodrug thereof, wherein:
• R1 is fluoro, chloro, or —C(J1)2CN;
• each J1 is independently H or C1-2alkyl;
• or
• two occurrences of J′, together with the carbon atom to which they are attached, form a 3-4 membered optionally substituted carbocyclic ring;
• R2 is H;
• halo;
• —CN;
• NH2;
• a C1-2alkyl optionally substituted with 0-3 occurrences of fluoro;
• or a C1-3aliphatic chain wherein up to two methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —C(O)—, or —S(O)n—;
• R3 is H;
• halo;
• C1-4alkyl optionally substituted with 1-3 occurrences of halo;
• C3-4cycloalkyl;
• —CN;
• or a C1-3aliphatic chain wherein up to two methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —C(O)—, or —S(O)n—;
• R4 is —O—, wherein —O— is substituted with one JQ;
• JQ is Q2;
• or a C1-8aliphatic chain wherein up to three methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —C(O)—, or —S(O)n—;
• wherein JQ is optionally substituted by 0-3 occurrences of JR;
• Q2 is a 3-7 membered fully saturated, partially unsaturated, or aromatic monocyclic ring having 0-3 heteroatoms selected from oxygen, nitrogen, and sulfur;
• or a 7-12 membered fully saturated, partially unsaturated, or aromatic bicyclic ring having 0-5 heteroatoms selected from oxygen, nitrogen, and sulfur;
• each JR is independently —CN;
• halo;
• ═O;
• —*0;
• Q3;
• or a C1-6aliphatic chain wherein up to three methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —C(O)—, or —S(O)n—;
• wherein each JR is optionally substituted with 0-3 occurrences of JT;
• or
• two occurrences of JR on the same atom, together with the atom to which they are joined, form a 3-6 membered ring having 0-2 heteroatoms selected from oxygen, nitrogen, and sulfur;
• wherein the ring formed by two occurrences of JR is optionally substituted with 0-3 occurrences of JX;
• or
• two occurrences of JR, together with Q2, form a 6-10 membered saturated or partially unsaturated bridged ring system;
• each Q3 is independently a 3-7 membered fully saturated, partially unsaturated, or aromatic monocyclic ring having 0-3 heteroatoms selected from oxygen, nitrogen, and sulfur;
• or a 7-12 membered fully saturated, partially unsaturated, or aromatic bicyclic ring having 0-5 heteroatoms selected from oxygen, nitrogen, and sulfur;
• each JT is independently —CN;
• ═O;
• a C1-6aliphatic chain wherein up to two methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —C(O)—, or —S(O)n—;
• or a 3-6 membered non-aromatic ring having 0-2 heteroatoms selected from oxygen, nitrogen, and sulfur;
• wherein each occurrence of JT is optionally substituted with 0-3 occurrences of JM;
• or
• two occurrences of JT on the same atom, together with the atom to which they are joined, form a 3-6 membered ring having 0-2 heteroatoms selected from oxygen, nitrogen, and sulfur;
• or
• two occurrences of JT, together with Q3, form a 6-10 membered saturated or partially unsaturated bridged ring system;
• each JX is independently —CN;
• halo;
• or a C1-4aliphatic chain wherein up to two methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —C(O)—, or —S(O)n—;
• each JM is independently halo or C1-6aliphatic;
• n is 0, 1, or 2;
• and
• each R is independently H or C1-4aliphatic.